1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method thereof.
2. Description of the Related Art
As semiconductor devices are micro-fabricated, for example, in a device with a capacitor mounted therein such as a DRAM element, means capable of not reducing the capacitance of the capacitor has been required. With regard to one of such means, a capacitance insulating film (dielectric film) having high permittivity has been developed. Japanese Patent Laid-Open No. 2007-318147 discloses metal oxides such as titanium oxide (TiO2) or zirconium oxide (ZrO2) as a capacitance insulating film having high permittivity for a capacitor.
If this film is applied to a capacitor, small leakage current, as well as high permittivity, is important. As disclosed in Japanese Patent Laid-Open No. 2009-059889 and Japanese Patent Publication No. 2008-526017, there has been proposed a method of laminating an insulating film consisting of a plurality of materials in order to reduce leakage current.
In addition, as disclosed in Japanese Patent Laid-Open No. 2007-201083, there has been proposed a method of oxidizing a surface of a lower layer prior to depositing an insulating film to improve a leakage current characteristic.